1. Field of the invention:
The invention relates to a polymer material which can be used for trapping byproducts and excess reactants in a reaction medium.
2. Brief Description of the Related Art
During the performance of a chemical reaction in order to prepare a desired product, undesirable byproducts are often obtained and have to be removed. In addition, the reaction medium may comprise excess reactants which also have to be removed. The use has been envisaged of polymers on which the undesirable compounds may become fixed.
The proposal has been made to use polyimines immobilized on a support for removing acidic compounds in an organic solvent. For example, DE 101 43 171 discloses a process for the preparation of a material for the removal of acids from an aprotic organic liquid, said material being composed of a polyalkyleneimine fixed to a support, for example silica. Yoshida Hiroyuki (Ind. Eng. Chem. Res.; vol. 33, No. 4, April 1994, pp. 854-859) describes the adsorption of a strong acid on a weakly basic exchanger composed of a polyethyleneimine fixed to a highly porous chitosan. JP 62216641 discloses a polyethyleneimine having a molecular weight of greater than 5000 adsorbed on a support (for example, a porous resin) and its use as adsorbent for strong acids, surfactants or heavy metals. The polyimine is adsorbed on the porous resin by immersion of the resin in a polyimine solution. It is thus a polyimine soluble in organic solvents which is immobilized on a support. The document U.S. Pat. No.5,162,404 discloses a sponge composed of cellulose and an “immobilized” polyethyleneimine fixed to the cellulose. The polyethyleneimine is a water-soluble branched polymer which comprises primary, secondary or tertiary amine groups separated by —CH2CH2- groups and which is rendered insoluble by crosslinking using a halogenated or nonhalogenated carboxylic acid or a polyhalogenated aliphatic compound of low molecular weight which reacts with the N atoms of the amine groups. In all these processes, however, there are a number of disadvantages to the immobilization of the polyimine on a support. First, the preparation of the immobilization support requires two stages (preparation of the polyimine and then fixing of the polyimine on the support), which increases the production costs. Secondly, for a given amount of support, the number of working functional groups is markedly lower when the polyimine is fixed to a support.
The proposal has been made to use an insoluble polymer as immobilization agent for a compound in solution. The polymers conventionally used are poly(styrene-divinyl-benzene)s carrying reactive functional groups which make possible the fixing of the compounds to be removed (cf. WO97/42230 and J. Chem. Soc., Perkin Trans. 1, 2000, p. 4133-4195). However, the polymers of this type cannot be used in aqueous media or in methanol. In addition, they have a relatively low level of active functional groups, which limits their performance.